for people who care about the West

The Ghosts of Yosemite

Scientists from the past bring us a message
about the future

Biologist Joseph Grinnell was
a world-class researcher, but he wasn't always the most pleasant of
traveling companions. "We'd be sitting in camp, and we'd both be
skinning," recalled naturalist Ward Russell, who spent years
helping Grinnell trap, skin and otherwise document the wildlife of
California. "Pretty soon, he'd throw a rat over to me, and he'd
say, 'Here, Russell, finish this one up,' and he'd just ... pick up
his notebook, and start writing."

Despite his dubious
camp etiquette, Grinnell's devoted record-keeping led to one of the
most famous datasets in modern biology. During their travels
throughout California between 1904 and the late 1930s, Grinnell and
his colleagues snared or shot more than 20,000 mammal, bird,
reptile and amphibian specimens, took about 2,000 photographs, and
filled 13,000 journal pages with erratic penmanship and beautifully
detailed observations. Their portrait of the natural diversity of
California remains unmatched in its scope and depth.

Grinnell, the founding director of the Museum of Vertebrate Zoology
at the University of California at Berkeley, was by all accounts a
dedicated, methodical researcher. His field journal, which he kept
until just five days before his death in 1939, numbered more than
3,000 pages. He helped build the museum's store of animal skins and
skeletons, an international collection now ranging from a hippo
skull the size of an easy chair to shrew skeletons no larger than a
thumb.

Grinnell was interested in far more than simply
cataloguing types and numbers of critters, what some modern
biologists dismiss as "stamp collecting." His exacting protocols
required collectors to not just record each find, but also to take
detailed notes on the surroundings and the weather. Using these
reams of information, Grinnell studied the intricate relationships
between animals and their habitats, developing theories still
taught in college biology courses.

Yet in 1910, Grinnell
predicted that the real value of his and his colleagues'
painstaking fieldwork would not "be realized until the lapse of
many years, possibly a century." Change was clearly part of the
natural world, he wrote. But he also saw "vastly more conspicuous"
transformations of the environment in the speedy deforestation,
cultivation, and irrigation of the West. He believed that in the
future, scientists would return to some of his more than 700 study
sites, and use his findings to chart these changes.

That
future is now. On a gray August morning, nearly a century after
Grinnell wrote those words, I shoulder a backpack on the east side
of Yosemite National Park and set off into a light but steady
drizzle. I'm not a scientist, but after years spent working and
playing with biologists, I've acquired a secondhand sense of
scientific curiosity. This hike is a welcome chance to indulge it.

Stored in my increasingly soggy pocket are two maps. One,
a reproduction of a map drawn in 1915 by Grinnell's colleague,
Charles Camp, has so many elegant squiggles and crosses that it
looks like a map to buried treasure. The other, a slice of
topographic cartography showing the same terrain, was e-mailed to
me just a few days earlier by one of Grinnell's intellectual
descendants.

In the time between these maps, startling
things have happened in Yosemite, and so far, their causes are
largely unacknowledged by the National Park Service. Just as
Grinnell foresaw, his data are providing valuable evidence of
conspicuous change in the natural world. But even the prescient
Joseph Grinnell didn't count on global warming.

I hike up
a long, gently sloping glacial valley, the miles quietly unrolling
behind me. I'm so distracted by the toothy granite peaks ahead, and
the glassy creek beside the trail, that I hardly notice the
worsening weather. By mid-afternoon, when I reach the cluster of
tents that form the modern-day Grinnell camp, the morning's showers
have turned into a cold, soaking downpour. I gratefully peel off my
clammy raingear and don the first dry clothes I'm handed —
which turn out to be a pair of Jim Patton's pants.

Patton, the curator of mammals at the Museum of Vertebrate Zoology
and a retired Berkeley professor, doesn't seem fazed by our unusual
introduction, the terrible weather, or much else. A wiry man with a
booming voice and ready laugh, Patton has spent much of his career
in Latin America, where he discovered several new species of
rodents and other creatures, and had a genus of speckled tree rats
named in his honor.

For Patton and his wife, Carol, an
elementary-school speech pathologist who joins most of his research
expeditions, a summer rainstorm in the Sierra is well short of a
crisis. This, after all, is a couple who were once shipwrecked in
the Gulf of California, with no provisions save a chocolate cake.
("It was a chocolate cake packed in brownies," says Jim, as if the
brownies were key to their survival.)

For the past week,
the Pattons and Les Chow, a wildlife biologist with the U.S.
Geological Survey, have been working near the head of Lyell Canyon.
Their camp, sheltered by a thick stand of square-browed whitebark
pines, sits just below Lyell Glacier, the largest glacier in
Yosemite. On the afternoon I arrive, the valley is cloaked in
clouds, but it still offers what the peripatetic John Muir called,
in an 1890 description, "a sublime and finely balanced picture."

Several researchers have mined the Grinnell data during
the past nine decades — herpetologist Gary Fellers used it in
the early 1990s to document a dramatic decline in amphibians in the
Yosemite area — but no one has ever attempted a broad
resurvey of the sites. Now, Jim Patton and other researchers
associated with the Museum of Vertebrate Zoology, inspired by
Grinnell's writings, hope to revisit about a third of the
California sites by the museum's centennial in 2008. With funding
from the Geological Survey and the Yosemite Fund, a nonprofit
organization that supports research in the park, biologists began
in 2003 to study 40 sites along Grinnell's "Yosemite Transect."

The morning after I arrive in camp, our group awakens to
clear blue skies and a dusting of snow on the highest peaks. We're
not the first to shiver through the night here: "This north slope
of Mt. Lyell must be one of the coldest places in California,"
Grinnell associate Charles Camp grumbled in his 1915 field journal.

The current work in Lyell Canyon is, in many ways, a
deliberate re-enactment. I follow Les Chow as he checks a long row
of mammal traps on a nearby talus slope, just as the Grinnell team
did here each day. I watch Jim Patton skin a few unlucky specimens
with a small pair of scissors, then record his findings and
observations using the exacting Grinnell method. Patton even stores
his trays of animal skins in the same scuffed crates once used by
Grinnell and his colleagues; the wooden boxes, originally designed
to carry cans of lard, have survived a century of nearly constant
use.

For Patton, the project is also a journey into his
scientific heritage. Grinnell and his colleagues often wrote down
their musings about the natural world, and Patton sometimes dips
into their journals during his days in the field. Grinnell pondered
the flocking behavior of redwing blackbirds, and wondered how birds
responded to the roar of the waterfalls in Yosemite Valley. Charles
Camp, one Sunday in 1915, proclaimed that "The Lord hath sent us a
wolverine," and made careful sketches of the animal's head and
paws, asking in a marginal note if its feet were webbed for walking
on soft snow. These voluminous notebook entries, with their
imperfections, their detours, and their moments of clarity, exude
the excitement of discovery.

"To be at the same spot, the
same rock outcrop, and to be able to read what they were seeing and
thinking ..." Patton shakes his head. "The only reason we have this
opportunity is that Grinnell was fanatic about what he did."

Field science has changed a bit since the days of Joseph
Grinnell. In the Lyell Canyon camp, we eat rehydrated dinners out
of foil packets instead of cooking on an open fire, and we eschew
worsted wool in favor of Gore-Tex. Some researchers store their
Grinnellian journals on Palm Pilots, instead of in the traditional
lined looseleaf notebooks. And while Grinnell used stacks of
"museum specials," a sort of burly mousetrap, to break the backs of
tens of thousands of small mammals, Patton and his crew now trap
their subjects alive in slim aluminum boxes, often releasing them
unhurt.

But the most significant difference between the
old and new Grinnell expeditions lies inside the traps. When Patton
first visited Lyell Canyon in 2003, he opened one of his aluminum
boxes to find a small mouse with remarkably large ears. "I thought,
'What the heck is this thing doing here?' " says Patton. "I was
dumbfounded." Its huge ears immediately introduced it as a
piñon mouse, which, as its name suggests, is a familiar
resident of the lower-elevation piñon pine forests of the
Sierra Nevada.

On the east side of the Sierra, Grinnell
and his assistants only saw piñon mice below 7,000 feet, a
finding confirmed by other researchers throughout the central part
of the range. Patton's group found numerous mice frolicking in the
talus slopes of Lyell Canyon, 10,200 feet above sea level and about
eight miles from the nearest Grinnell sighting. The distance was
too great to be the work of just a few wandering individuals; it
was clear to Patton that the range of the piñon mouse, and its
habitat, was far different now than in 1915.

"They're
common, and they're easily identified," says Patton. "If they had
been up here before, (Grinnell and his compatriots) would have seen
them."

The new Yosemite crew uncovered more changes. Four
other small mammals have expanded their turf in the park,
increasing the upper limits of their ranges by an average of 2,000
vertical feet. The alpine chipmunk, two high-elevation ground
squirrels — including the Belding's ground squirrel, known as
the "picket pin" for its ramrod-straight alarm posture — and
a small relative of the rabbit called the pika have retracted their
haunts uphill, drawing in the lower edge of their ranges by an
average of 1,700 vertical feet. At least two species of small
mammals, a chipmunk and a woodrat, have dramatically shrunk the
overall size of their ranges, and are now extremely rare in the
park.

Ornithologist Andrew Rush, who recently revisited
the Grinnell sites in Yosemite, also saw and heard some surprises.
In Lyell Canyon alone, he recorded 17 bird species not mentioned by
the Grinnell team, many of them riparian and wetland species more
familiar at lower elevations. Some of these species, such as the
blue-winged teal and the mallard, were even breeding in the
canyon's high-elevation meadows.

The Grinnell survey and
resurvey represent just two snapshots in time, and what happened in
the intervening years is largely unknown. But studies of particular
species in the area help fill in the gaps, and confirm that neither
Grinnell nor his modern followers witnessed a fleeting anomaly.

So what's going on in Yosemite? Fire suppression, with
its transforming effects on habitat, has certainly played a part in
the rearrangements of wildlife at lower elevations. It may also
explain why a couple of small mammal species moved downhill in the
park, defying the overall trend. Yet in alpine areas such as Lyell
Canyon, Grinnell photographs from 1915 show that its forests and
meadows looked almost the same as they do today.

There is
little question, however, that the entire park is warmer than it
was during Grinnell's time. Snow is melting earlier in the spring,
and Lyell Glacier, like other glaciers throughout the Sierra, is
disappearing. Researchers at Portland State University found, using
another series of historic photographs, that the surface area of
the western lobe of Lyell has shrunk 30 percent since 1883, and the
eastern lobe has contracted 70 percent.

Weather records
from Yosemite Valley show a 9 degree Fahrenheit increase in mean
minimum temperatures over the past century. Though weather data
from higher elevations are spotty, Museum of Vertebrate Zoology
researcher Robert Hijmans estimates that mean minimum temperatures
throughout the central Sierra rose 5 degrees Fahrenheit over the
last 100 years.

The vast majority of scientists say
humans have a lot to do with such changes, which are now observed
around the world. They say the rising concentration of carbon
dioxide and other greenhouse gases in our atmosphere — due in
large part to cars, coal-fired power plants, and other human
inventions — bears significant blame for the planet's warming
climate.

In high, relatively undisturbed places such as
Lyell Canyon, these rising temperatures — and their various
effects on the landscape — are the most dramatic changes in
the environment over the past century, and they are the most
obvious explanation for the shifting alpine wildlife of Yosemite.
For some species, it appears, just a few degrees' difference in
temperature makes home uncomfortable, and previously inhospitable
habitat more welcoming. "For the pika, the alpine chipmunk, and the
Belding's ground squirrel, I don't know what else to link it to,
other than climate change," says Patton.

Back at the
Museum of Vertebrate Zoology, museum director Craig Moritz agrees.
"This is a work in progress," he cautions, "but my gut feeling is
that we've got a whopping climate change signature."

Thus
the legacy of Joseph Grinnell survives, informing a new world.
"Grinnell was one of those classic early ecologists that snobby
scientists, towards the end of the 20th century, would dismiss as
'descriptive,' " says Raphael Sagarin, a researcher at the
University of California at Los Angeles who uses historical
datasets to study the effects of climate change. "Now we are seeing
how important good descriptions of nature really are."

On
the trail in Yosemite, I meet a pair of hikers, and I mention what
the Berkeley researchers are seeing — and not seeing —
in the park. One shrugs. "Things change, man," he says. "That's
just the way it is."

In one sense, he's right. But never
before have things changed in quite this way, for quite this set of
reasons. Never before have human activities shoved entire
communities of animals uphill, causing eerily consistent shifts
across huge and varied landscapes.

On another stormy
summer evening, back in the buzz and crackle of civilization, I
listen to ecologist Camille Parmesan unsettle a crowd. She tells
her audience, gathered at an environmental center in Aspen, Colo.,
that five species of tropical butterflies have just been recorded
in Texas, and some are trying to breed as far north as Austin
— about 700 miles north of their usual range. "They cannot
handle a freeze," says Parmesan, a professor at the University of
Texas at Austin, as she describes a strictly tropical group of
species known as clearwings. "It's very bizarre to be seeing them
up in Texas."

Butterfly populations are making similar
northward leaps in California and throughout Europe, she reports.
Meanwhile, several species of tropical dragonflies have moved
northward into Florida, and southern Louisiana now has several
dozen permanent populations of rufous hummingbirds, a species that
once only visited in the summer.

Many species have also
disappeared from the southern and low-lying parts of their ranges.
The plants they depend on may now dry up too early; false springs
may destroy vulnerable populations; or several subtle effects of
warming temperatures may combine to drive animals out, or simply
kill them. For instance, many low-elevation populations of pikas,
the alpine rabbit relative, have disappeared in the Great Basin
during the past 80 years. Such local extinctions can crunch a
species' overall genetic diversity, making it more vulnerable to
disease and habitat shrinkage.

Consider the Quino
checkerspot butterfly, now on the endangered species list. It
appears to have lost the southern end of its range, in the Mexican
state of Baja California, to global warming, while habitat in its
northern haunts, in and around San Diego and Los Angeles, has been
largely erased by urbanization (HCN, 11/10/03: San Diego’s
Habitat Triage). "This is what has conservation biologists
worried," says Parmesan. "It's the combined effects of climate
change pushing things to want to shift around the globe, and human
habitat destruction ... preventing that movement."

Shifting species can also make life difficult for their new
neighbors. The red fox of northern Canada, which moved its range
600 miles northward in just 30 years, now threatens to outcompete
the smaller, less aggressive Arctic fox. In the cloud forests of
Costa Rica, toucans recently shifted to higher elevations, where
they jostle the quetzal — an emerald-feathered bird dependent
on cloud forest habitat.

In all of these cases, changes
in habitat - logging, farming, urbanization, and the like —
likely play some part. But the breadth and strength of the overall
trend is undeniable, and that trend clearly indicates that rising
temperatures are at work.

Parmesan, who co-authored a
2003 analysis of existing studies in the scientific journal
Nature

, estimates that biologists have now
collected "good quality data" on the effects of climate change on
more than 1,500 animal and plant species. Half those species have
clearly shifted upward or northward in recent decades, and
two-thirds are breeding earlier in the year. Only a handful are
moving to warmer climates, or breeding later.

Stanford
University biologist Terry Root, who led a similar analysis of the
field in 2003, reports that a consistent "fingerprint" of global
warming is perceptible on species "ranging from molluscs to mammals
and from grasses to trees."

Even if we quit adding
greenhouse gases to the atmosphere tomorrow, the planet would
continue to warm up. Researchers at the National Center for
Atmospheric Research in Boulder, Colo., call it the "climate change
commitment": What we've already pumped into the atmosphere will
cause global air temperatures and sea levels to rise, slowly but
significantly, over the next several centuries. Every day of new
emissions commits us to yet more warming, and deeper waters.

The Intergovernmental Panel on Climate Change, considered
the global scientific authority on the subject, foresees that
between 1990 and 2100, the earth's average surface temperature will
increase by between 2.5 and 10.4 degrees Fahrenheit. "The projected
rate of warming," the panel concluded in its most recent report,
"is much larger than the observed changes during the 20th century,
and is very likely to be without precedent during at least the last
10,000 years."

Yosemite National Park, like all our
national parks, is supposed to muffle these and other "vastly more
conspicuous" transformations wrought by humans, to use Joseph
Grinnell's words. "It would seem to me that national parks should
comprise pieces of the country in which natural conditions are left
altogether undisturbed by man," Grinnell wrote to Yosemite
Superintendent W.B. Lewis in 1920. Yet the modern-day Grinnell team
has found that when it comes to global warming, Yosemite is no
refuge.

"Places like Yosemite mean so much to so many
people," Jim Patton reflects. "People think we've preserved this
piece of the environment, but we haven't. The high-elevation
species, those that seem to be retracting upwards, have no place to
go — so when they go, they're gone, and they're never coming
back."

How do we respond to such dire forecasts?
Protecting more land in more diverse habitats is the obvious
answer, so that as the earth warms, affected animals will have more
places to go. The Nature Conservancy's Global Climate Change
Initiative, for example, is researching the current and future
impacts of climate change on wildlife and habitat, with an eye to
incorporating its findings into conservation planning.

But turning theory into reality is expensive, and politically
tricky. While many land trusts and other conservation groups are
working to connect existing reserves with corridors of protected
habitat, there are as yet few — if any — natural areas
intended specifically to cushion the effects of global warming on
biodiversity. What's more, some already protected areas are hemmed
in by development, making it difficult for them to expand.

For the most part, managers of existing parks and
reserves must work within their boundaries, and when it comes to a
global problem like climate change, that's a frustrating
proposition. Parks certainly can't put the brakes on climate change
by themselves, and they can't grow their mountains to create more
habitat for pikas.

Some park researchers and managers,
including David Welch of Parks Canada, suggest that parks dedicate
themselves to reducing other stresses - invasive species, or haze,
or human impacts — in hopes of buffering the effects of
climate change on wildlife and habitat. Others advise transplanting
species, or working with other land managers to protect habitat
corridors.

"I think it's going to take a lot of thought,"
says Kathy Jope, chief of natural resources for the Pacific West
region of the Park Service. "There's a lot of uncertainty about
exactly what we should do." She points out that moving a few
animals won't preserve an ecosystem, and that exotic species travel
corridors, too, often more quickly than their native competitors.
Clever solutions have an irritating habit of leading to new
problems.

One thing that national parks can do is fire
the public imagination. "Parks are treasured icons," says Welch,
who is helping devise a climate-change adaptation strategy for
Canadian parks. "There's a lot we can do with outreach and
education."

Yet in the United States, park officials are
often loath to speak openly about the effects of global warming on
their own resources. "Scientists, naturalists and educators in
every park are facing it, and they see that it's really powerful
and inescapable," says one park official, who asked not to be
named. "But parks have to be very subtle in how they approach these
things. The biological reality we see around us, and the reality
the (Bush) administration sees, do not come together very well."

The Bush administration has long emphasized the
uncertainties inherent in climate change research, and opposed any
mandatory controls on greenhouse gas emissions. Though President
Bush did say, just prior to the Group of Eight Summit in Scotland
in July, "I recognize that the surface of the Earth is warmer, and
that an increase in greenhouse gases caused by humans is
contributing to the problem," the administration's position on
emissions controls has not changed.

Many park staffers
fear the consequences of undercutting this position, even
indirectly. Though park staff say they have not received specific
instructions from the top on global warming, the president is,
after all, their boss, and many feel their words and actions are
scrutinized. "I've never seen an administration that's extended its
reach so far down in the system," says the unnamed official.

By 2030, scientists predict, even the largest glaciers at
Glacier National Park will be gone; you may live to hike in a
glacierless Glacier. But the park still provides little information
to the public about the known causes and effects of climate change.
"We've had visitors ask, 'Why aren't you saying more about global
warming?' " says Leigh Welling, director of the park's Crown of the
Continent Research Learning Center, "and I think that's a fair
question."

Even in the face of mounting scientific
evidence, some park officials are reluctant to fully acknowledge
the issue. "How possible climate change could impact the park's
resources is still unknown," says Niki Nicholas, chief of resource
management and science at Yosemite. "Will temperatures be higher or
lower, in which places, and in which time of year? Those questions
are all unanswered."

In place of an emphatic and
straightforward message about global warming, national parks have
the Climate Friendly Parks program, a modest joint effort of the
Park Service and the Environmental Protection Agency. With a
$200,000 annual budget and the part-time attention of three Park
Service employees, the program encourages parks to voluntarily
reduce their own greenhouse gas emissions and educate the public
about their efforts. Many parks, including Yosemite, have adopted
some energy-efficient technology, perhaps hoping that fleets of
hybrid buses and arrays of solar panels will quietly inform and
inspire their visitors.

Some parks are beginning to talk
plainly about the impacts of global warming, but their approach
remains cautious. Glacier is revising its "messaging" on climate
change, and plans to make more detailed and explicit information
available to visitors. In Sequoia National Park, a forthcoming
visitors' center exhibit will discuss global warming's implications
for the park. "We don't try to tell people what will happen," says
Sequoia chief of interpretation Bill Tweed, "but we do ask them to
ponder what might happen."

Michael Soukup, Park Service
associate director for natural resource stewardship and science,
gingerly endorses these efforts. "I believe that the science is
fairly clear, and the last I heard about the politics of it,
everyone was willing to agree that there was change afoot," he
says. While the degree of humanity's contribution to climate change
is still up for debate, he adds, "It'd be nice for park visitors to
hear a clearer message that we need to be careful in our energy
consumption and efficiency."

But for the Park Service,
facing climate change also means facing a fundamental quandary.
Back when Congress created it in 1916, the agency was charged with
protecting park resources, including wildlife, "unimpaired for the
enjoyment of future generations." Climate change is looking more
and more like an unavoidable impairment.

"For traditional
parks, those that preserve large amounts of biology, climate change
challenges the mission we've had since year one," says Bill Tweed.
"We're not going to save it all - I don't see how that's possible.
So what is our mission?"

There are no easy answers.
Change is surely constant in nature; even the most casual visitor
to Yosemite accumulates stories about lightning and rain and soggy
gear, and stands awed before the work of glaciers and wildfires.
But global warming is a far different, and much stranger, creature,
one that threatens the very nature of the national parks
themselves.

Perhaps part of the new mission of the Park
Service is to speak openly about this exceptional change — to
talk about why the piñon mouse is no longer really a
piñon mouse, and why the pika is running out of room. In the
90 years since Charles Camp drew his map of Lyell Canyon, Yosemite
has changed in ways he could not have imagined. Thanks to the work
of Joseph Grinnell and his colleagues, the Park Service can now
explain why.